Microdroplets show great promise as a new high-throughput technology in chemistry, biochemistry and molecular biology. Microdroplets can be generated at rates in excess of several thousands per second and accurately formulated using minute amounts of small molecules, DNA, proteins or cells. Furthermore, integrated active elements can be used to control individual droplets. For example, we have previously described, in WO2009/050512, a technology that bridges the fields of microdroplets and continuous flow microfluidics by extracting on-chip the contents of microdroplets and incorporating them into a continuous stream.
Traditionally microdroplets have served as “microreactors” for controlled processing of the contents. For example, Rain Dance Technologies Inc, have technology to fuse microdroplets holding a specific primer pair with other microdroplets containing the DNA to which the specific primers are to be attached. Other background prior art can be found in US2010/0022414 and in US2010/0137163.
The inventors have recognised that microdroplets may, alternatively, be used in other ways.